This is exactly how I feel! I have been doing marathons and half marathons for years. Last year, I was signed up for a half in April, found out I was pregnant in January, and had a loss in Feb. Technically I guess I could have gotten my training back on course after my miscarriage, but I really wasn't up for running for awhile. So that was the first time I had ever signed up for a race and not run it. I felt like a failure. Since then, I haven't signed up for any races longer than five miles becuase I am constantly hoping that I'll be pregnant by "then". And most recently, my RE suggested that I should cut back on running because my losses have been unexplained and he said it would be one less thing possible cause to consider.
But the past several years have been punctuated by the cycle of training and then racing, and I miss it so much. My running club friends don't know what I'm going through, and they are all kind of like, why don't you race anymore? Running makes me "me" and now I can't do it. It's so frustrating.
I see those jogging strollers and just hope and dream that I'll be running with my baby one day. But it absolutely sucks right now. (All things TTCAL and IF suck, though!)